I just intalled my 34e rad valve on my 1999 YZ250 and took it for a spin... talk about an ear-to-ear grin!! The power difference was incredible!! The low end and midrange torque is crazy with that thing. My bike wants to wheelie all the time now! Didn't even have to rejet or anything. Fits perfectly (no mods necessary) and looks better than OEM parts did. It's preassembled from the factory. It came with instructions a new gasket and what I think was a spacer (I left that out). I strongly recommend this to anyone that wants to bolt on more power in less than an hour.